新疆卡鲁安硬岩型锂矿床花岗岩与伟晶岩成因关系:锆石U-Pb定年、Hf-O同位素和全岩地球化学证据  

Genetic relationship between granite and pegmatite in Kalu’an hard-rock-type lithium deposit in Xinjiang:results from zircon U-Pb dating,Hf-O isotopes and whole-rock geochemistry

作　　者：刘涛 田世洪 王登红[2] 张玉洁[2,3] 李贤芳 侯可军 杰肯·卡里木汗[4] 张忠利 王永强 赵悦 秦燕[2] LIU Tao;TIAN Shihong;WANG Denghong;ZHANG Yujie;LI Xianfang;HOU Kejun;JIEKEN·Kalimuhan;ZHANG Zhongli;WANG Yongqiang;ZHAO Yue;QIN Yan(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang,330013;MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing,100037;School of Earth Science and Mineral Resources,China University of Geosciences,Beijing,100083;No.701 Geological Team,Bureau of Nonferrous Geo-exploration of Xinjiang Uygur Autonomous Region,Altay,836500)

机构地区：[1]核资源与环境国家重点实验室,东华理工大学,南昌330013 [2]自然资源部成矿作用与资源评价重点实验室,中国地质科学院矿产资源研究所,北京100037 [3]中国地质大学地球科学与资源学院,北京100083 [4]新疆维吾尔自治区有色地质勘查局七〇六队,新疆阿勒泰836500

出　　处：《地质学报》2020年第11期3293-3320,共28页Acta Geologica Sinica

基　　金：国家重点研发计划“深地资源勘查开采”专项“锂能源金属矿产基地深部探测技术示范”项目(编号2017YFC0602700)“同位素地球化学与配套深部探测技术研究”课题(编号2017YFC0602705);东华理工大学高层次人才引进配套经费(编号1410000425)联合资助的成果。

摘　　要：卡鲁安锂矿床位于新疆阿尔泰造山带,是中国主要的稀有金属矿床产地之一,但前人工作程度较低、研究工作较少,其岩石成因和成矿机制有待于深入系统研究。文章系统研究了新疆卡鲁安含矿伟晶岩、无矿伟晶岩、外围花岗岩、外围伟晶岩、角岩、片岩、板岩等全岩样品的主量元素、稀土微量元素、Pb-Sr-Nd同位素以及锆石U-Pb定年和Hf-O同位素,旨在揭示卡鲁安矿区花岗岩与伟晶岩形成时代、岩浆起源及其演化过程,进而探讨两者之间的成因联系。年代学数据显示,卡鲁安矿区外围黑云母花岗岩、含矿伟晶岩和外围伟晶岩锆石SIMS U-Pb年龄分别为407.9±2.3Ma(n=25,MSWD=1.4)、205.0±12.0Ma(n=6,MSWD=2.2)和205.0 Ma。外围黑云母花岗岩以高SiO2(71.16%~75.39%)、高CaO(1.15%~1.85%)、低Fe2O3/FeO(<0.4)、过铝质(A/CNK=1.04~1.09)和富碱性暗色矿物(>8%)等为特征。在稀土微量元素组成方面,具有弱分异的Zr/Hf(25~55)和Nb/Ta(5.4~8.8)比值,相对富集Rb、Th、U、Pb、Hf和LREEs,亏损Ba、Nb、Sr、P、Ti等元素,为典型的弱分异S型花岗岩,其源岩可能为一套变质沉积岩。在Hf-O同位素组成方面,含矿伟晶岩(ε(Hf)(t)=-0.2~2.0,δ^18O=7.88‰~10.87‰)和外围伟晶岩(ε(Hf)(t)=-0.7~8.1,δ^18O=6.87‰~9.48‰)与外围黑云母花岗岩(ε(Hf)(t)=1.3~7.4,δ^18O=8.62‰~10.08‰)具有一致性,指示含矿伟晶岩和外围伟晶岩与外围黑云母花岗岩可能具有相同的物质源区。黑云母花岗岩与片岩、板岩具有类似的稀土微量元素配分模式、类似的Pb-Sr-Nd同位素组成和Nd同位素模式年龄,指示由片岩、板岩部分熔融产生的;同时,含矿伟晶岩和无矿伟晶岩也展现出类似的稀土元素和微量元素配分模式,但其∑REE含量明显低于外围黑云母花岗岩,表明这些伟晶岩可能与外围黑云母花岗岩具有成因关系。但黑云母花岗岩比伟晶岩成岩时代早近200 Ma,所以伟晶岩不是外围黑云母花�The Kalu’an lithium deposit is located in the Altay orogenic belt in Xinjiang,which is one of the main rare metal deposits in China.Due to less research work in the Kalu’an lithium deposit,its petrogenesis and metallogenic mechanisms need to be systematically studied.In this paper,results of major elements,trace elements,rare earth elements(REEs)and Pb-Sr-Nd isotopes analyses of spodumene-bearing pegmatites,spodumene-barren pegmatites,outer granites,outer pegmatites,hornstones,schists and slates,and zircon U-Pb and Hf-O isotopic data of outer granites,spodumene-bearing pegmatites and outer pegmatites from the hard-rock-typelithium deposit in Kalu’an,Xinjiang are used to determine the formation age,magmatic origin and evolutionary process of granite and pegmatite,and to further investigate their genetic relationship.Geochronological data indicate that the SIMS U-Pb ages of zircons from the outer biotite granites,spodumene-bearing pegmatites and outer pegmatites are 407.9±2.3 Ma(n=25,MSWD=1.4),205.0±12.0 Ma(n=6,MSWD=2.2),and 205.0 Ma respectively.The outer biotite granites from Kalu’an are characterized by high SiO2(71.16%~75.39%),CaO(1.15%~1.85%),low Fe2O3/FeO(<0.4).They are also peraluminous(A/CNK=1.04~1.09)and contain alkaline dark minerals(>8%).In terms of trace and REE compositions,outer biotite granites have weakly differentiated Zr/Hf(25~55)and Nb/Ta(5.4~8.8)values,are relatively enriched in Rb,Th,U,Pb,Hf and LREEs,and depleted in Ba,Nb,Sr,P and Ti.These geochemical features indicate that Kalu’an biotite granites belong to typical weakly differentiated S-type granites,whose source rocks may be a set of metamorphic sedimentary rocks.Spodumene-bearing pegmatites and outer pegmatites have consistent Hf-O isotopic compositions with outer biotite granites:εHf(t)=-0.2~2.0 andδ^18O=7.88‰~10.87‰for spodumene-bearing pegmatites,εHf(t)=-0.7~8.1 andδ^18O=6.87‰~9.48‰for outer pegmatites,andεHf(t)=1.3~7.4 andδ^18O=8.62‰~10.08‰for biotite granites,suggesting that they may have the same source

关 键 词：花岗岩 伟晶岩 锆石U-PB定年 地球化学 岩石成因 成因关系 硬岩型锂矿床 新疆卡鲁安 

分 类 号：P588.1[天文地球—岩石学] P597.3[天文地球—地质学] P618.71